Spin orbit torque magnetic random access memory (SOT-MRAM) has attracted massive research interests due to its promising application potential in high-speed computing systems (e.g. upper level caches). Here we propose an erasable spintronics memory based on a novel field-free SOT switching mechanism. The data writing is achieved through erase and subsequent program operations, both of which are implemented with unidirectional currents. For improving the storage density, the erase operation is shared by multiple bit-cells, meanwhile some access transistors could be replaced with diodes thanks to the use of unidirectional currents. The simulation results demonstrate that the proposed erasable spintronics memory is featured by sub-nanosecond write speed, femto-joule write energy and higher storage density than the conventional SOT-MRAMs.